Duct sensors are commonly used to sense environmental conditions such as temperature and/or humidity. They may, for instance, be employed in installations for heating, ventilation, and/or air conditioning. Commercial, industrial and/or residential sites typically provide such installations with duct sensors.
A typical duct sensor comprises a tubular housing and an elongated circuit board arranged inside the housing. The circuit board inside the tubular housing may provide an electric and/or an electronic circuit to process and to analyze signals obtained from a sensor. The printed circuit board may extend outside the tubular housing.
A cover is commonly employed to separate sections of the same (printed) circuit board inside and outside the tubular housing. The cover typically provides a duct such that the elongated circuit board passes through the cover. The duct also seals the elements of the sensor inside the tubular housing against ingress of fluids such as moisture. In doing so, the duct acts to protect the elements on the inside of the housing against corrosion.
To further protect against corrosion, the inside of the housing may be filled with a suitable moisture-impervious potting compound. By protecting the circuit inside the housing against ingress of fluids, any adverse influence of moisture on electric and/or electronic elements of the sensor is minimized. The moisture-impervious potting compound may also fill and/or impregnate any voids inside the protected part of the sensor, thereby enhancing electrical insulation inside the housing.
The U.S. Pat. No. 3,175,391 was granted in 1965 and discloses a humidity measuring device for measuring moisture in stacks of sheet material, such as stacks of paper. FIG. 1 of U.S. Pat. No. 3,175,391 shows a module assembly 18 arranged inside a housing 22. Apertures 23 are provided at one end of the housing 22 such that air may circulate through the apertures 23 into the housing 22. The module assembly 18 operates to sense humidity. Consequently, the module assembly 18 is arranged inside the housing 22 and in the vicinity of the apertures 23.
A terminal block 16 separates the end of the housing 22 with the apertures 23 from the other end of the housing. On the opposite side of the terminal block 16, various resistors R3, R4 act to process and analyze the signal from the humidity sensor. The resistors R3, R4 are arranged inside a notch 14 where they are cast in a suitable potting compound.
FIG. 9 of U.S. Pat. No. 3,175,391 shows the terminal block 16 and how it 16 is mounted to the housing 22. FIG. 9 and FIG. 4 depict two side lugs 43, one fastening member 19, 20 for each lug 43 and a finger 15 adjacent to the lugs 43. Each of the fastening members 19, 20 extends through one of the lugs 43. FIG. 11 shows that the fastening member 19 is engaged on the finger 15 through a threaded connection. Likewise, FIG. 9 shows the fastening member 20 engaged on a stud 60 mounted to the same finger 15.
The patent application US2007/0012087A1 was filed on 9 Feb. 2004. US2007/0012087A1 teaches a sensor.
The patent US006063249A issued on 16 May 2000. US006063249A discloses an oxygen sensor.